We are submitting this proposal in response to PA-02-150, "Services and Intervention Research with Homeless Persons Having Alcohol, Drug Abuse, or Mental (ADM) Disorders." This project seeks to better understand the barriers to responding to alcohol, drug and mental health (ADM) problems and homelessness within the changing welfare system. Public aid programs represent an important gateway into services for homeless and other indigent adults needing income support, housing, vocational rehabilitation, health care and behavioral health care. Sweeping policy changes under welfare reform are affecting public services for the homeless in ways that are not fully understood. The project utilizes secondary analyses of the NIAAA-funded Welfare Client Longitudinal Study, which includes representative samples of Temporary Aid to Needy Families and local General Assistance recipients. Study participants are being followed and re-interviewed over five years in the aftermath of welfare reform. The project supplements these secondary analyses with new ethnographic data on how service providers cope with the dilemmas of brokering services for the homeless, and on how homeless adults experience barriers to services. Proposed analyses develop profiles of the diverse service needs of homeless adults on public aid, examine how service providers respond to these needs in a real world setting, study the consequences of welfare reform policies for homeless clients over time, and identify barriers to the wider use of public services by homeless aid recipients. The project utilizes event history analysis to study how unstable housing, behavioral health problems and the use of services co-evolve over time in the lives of aid recipients. Data from ethnographic observation and interviewing of service providers offer a broader perspective on the organizational challenges to meeting the needs of homeless people on public aid.